SuDS in London - a guide

Glossary
Amenity
The quality of a place being pleasant or
attractive, ie, its agreeableness. A feature
that increases attractiveness or value,
especially of a piece of real estate or a
geographic location.
Anaerobic
An absence of oxygen
Anthropogenic soil profile
Where the upper profile of soil is changed
by human intervention and activity.
Appraisal period
The agreed time over which the costs and
benefits are assessed and then discounted.
Attenuation
An intervention to reduce peak flow and
increase the duration of a flow event.
Attenuation tank
A vessel which retains excess water and
slowly releases it in a controlled discharge
to a combined drain or watercourse.
Base flow
The normal level of subsurface water.
Basin
A ground depression acting as a flow
control or water treatment structure that
is normally dry, but is designed to detain
storm water temporarily.
Benefit cost ratio (BCR)
The net present value divided by the costs
(normally the capital and operational
costs).
Biodiversity
The diversity of plant and animal life in a
particular habitat.
Bioretention area
A depressed landscaping area that collects
runoff and percolates it through the soil
below the area into an underdrain; this
helps remove pollution.
Blue infrastructure
Describes all waterways, both natural and
man-made, in and around towns and cities.
BREEAM
The Building Research Establishment’s
Environmental Assessment Method.
It sets best practice standards for the
environmental performance of buildings.
Brownfield site
A site that has been previously developed.
Catchment
The area contributing surface water flow
to a point on a drainage or river system.
Can be divided into sub-catchments.
CIRIA
The Construction Industry Research and
Information Association.
Combined sewer
A sewer designed to carry foul sewage and
surface runoff in the same pipe.
Contaminated ground
Ground that contains substances that,
when present in sufficient quantities or
concentrations, can have detrimental
effects on the surrounding area.
Control structures
Components of a SuDS scheme which
control the rate at which water flows along
and out of the system.
Conventional drainage
The traditional method of draining surface
water using subsurface pipes to remove
water as quickly as possible.
Conveyance
140 Appendices